Machine tools refer to machines used for the purpose of machining metallic or non-metallic workpieces (hereinafter referred to as the “base materials”) into desired shapes and dimensions by means of appropriate tools by using various types of cutting or non-cutting methods.
Furthermore, machine tools may be basically classified into turning centers configured to machine base materials by rotating the base materials and moving tools and machining centers configured to machine base materials by rotating tools and moving the base materials.
FIG. 1 is a view showing a machine tool in which a conventional ram spindle is disposed, and FIG. 2 is a perspective view showing the conventional ram spindle and a conventional tool holder which are coupled to each other.
Referring to FIG. 1, in a conventional machine tool 10, a turntable 2 is disposed, an auto tool changer (ATC) accommodated in an ATC accommodation part 6 and a column 8 are disposed on a base 1, a cross rail 9 is disposed on the column 8, and a ram carriage 5 is disposed on a side of the cross rail 9.
A base material (not shown) to be machined is fastened to and rotated on the turntable 2, and the ram carriage 5 is movable in a direction parallel to a ground surface by means of the cross rail 9.
In this case, the ram carriage 5 is movable along a vertical transfer part 7 in a direction perpendicular to a ground surface. A ram spindle 4 is disposed at the distal end of the ram carriage 5, and a head block 3 is disposed at the free end of the ram spindle 4.
In other words, the ram spindle 4 disposed on the ram carriage 5 is moved along the cross rail 9 in the x-axis direction and along the vertical transfer part 7 in the z-axis direction, and is thus disposed at a location where a tool can machine the rotating base material through turning.
In this case, a tool holder 20 having a mounting depression 21 into which an insert (a tool) for machining a rotating base material is disposed may be mounted on the head block 3. The tool holder 20 is mounted in or detached and replaced from the ATC inside the ATC accommodation part 6 depending on the machining path and shape of a base material.
However, the method of replacing the tool holder 20 of the conventional machine tool 10 requires a long replacement time, and increases the number of required tool holders 20, thereby increasing the costs of the machine tool 10.
Furthermore, the individual tool holders 20 have minute differences, and thus a problem with the reliability of the degree of precision may occur due to the differences in machining distance attributable to inserts mounted into the tool holders 20.